fix(TASK-046): engine polish + wizard bypass + ETXTBSY retry

- unify hook base-env assembly on hooks::base_envs_parts (drop the
  hand-copied hook_base_envs in function/agents.rs; graph executor and
  spawn-result hooks now share the single construction site, test-pinned)
- factor the duplicated job.started dispatch in jobs.rs handle_start
  into one fire_job_started helper
- COYOTE_LLM_ERROR now carries the immediate error (to_string()),
  matching COYOTE_TOOL_ERROR; test pins the new format
- remove all stale #[allow(dead_code)] markers in src/hooks.rs
- test infra: rename install_warn_collector -> install_log_collector,
  add poison-symmetric warn_snapshot/debug_snapshot helpers, hoist a
  shared EnvVarGuard (TestConfigDirGuard now builds on it), add a
  same-fire payload-uniqueness test, and give global_tools env
  overrides the same malformed-JSON debug diagnostic as global_hooks
- inspection-only flags (--info et al) bypass the first-run wizard:
  missing config + info_flag returns Config::default() without writing
  anything, in both the sandbox and interactive arms (tests included)
- bound the shim-relocation test's exec in an ETXTBSY retry (10x50ms)
- document the intended 'roles' reserved-name asymmetry at
  resolve_bundle_name's gate

src/client/common.rs

@@ -579,9 +579,9 @@ fn llm_failed_extras(
     }
     extras.push((
         "COYOTE_LLM_ERROR",
-        // `{:#}` renders the whole context chain, so the root cause survives
-        // the `context(...)` wrapping the client trait defaults apply.
-        err.map(|err| format!("{err:#}"))
+        // The immediate error only, matching COYOTE_TOOL_ERROR; the context
+        // chain below it stays out of the env.
+        err.map(|err| err.to_string())
             .unwrap_or_else(|| "Aborted.".to_string()),
     ));
 
@@ -1862,12 +1862,10 @@ mod tests {
             failed.envs.get("COYOTE_LLM_STATUS").map(String::as_str),
             Some("429")
         );
-        assert!(
-            failed
-                .envs
-                .get("COYOTE_LLM_ERROR")
-                .unwrap()
-                .contains("error (status: 429)")
+        assert_eq!(
+            failed.envs.get("COYOTE_LLM_ERROR").map(String::as_str),
+            Some("Failed to call chat-completions api"),
+            "the env must carry the immediate error only, not the context chain"
         );
         assert!(!failed.envs.contains_key("COYOTE_LLM_DURATION_MS"));
     }